Blade mountings and controls for road graders



Jan. 14, 1969 T. RlVlNlUS 3,421,589

BLADE .MOUNTINGS AND CONTROLS FOR ROAD GRADERS Filed Sept. 16, 1965Sheet of'4 FIE: 1

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BLADE MOUNTINGS AND CONTROLS FOR ROAD GRADERS Sheet 3 of 4 Jan. 14, 1969Filed Sept. 16, 1965 f BY a AM, W

Jan. 14, 1969 3,421,589

BLADE MOUNTINGS AND CONTROLS FOR ROAD GRADERS T. RIVINIUS Filed Sept.16, 1965 Sheet 1 of 4 WIEIIW I l V ENTOR. TA/Eobakt JP1400/04- lrrakansUnited States Patent 3,421,589 BLADE MOUNTINGS AND CONTROLS FOR ROADGRADERS Theodore Rivinius, 1011 Ave. B West, Bismarck, N. Dak. 58501Continuation-impart of application Ser. No. 362,740, Apr. 27, 1964. Thisapplication Sept. 16, 1965, Ser. No. 487,785 U.S. Cl. 1724.5 11 ClaimsInt. Cl. E02f 3/76; E02f 3/12 ABSTRACT OF THE DISCLOSURE A gradingmachine having a main frame and an earthworking blade mounted onto acircle frame which in turn is attached to the main frame. Linkages arepositioned on opposite sides of the circle frame for controlling thedepth of the earthworking blade and the transverse angle of the blade.The linkages hold the circle frame stable in fore and aft directions sothat the circle flame moves up and down in a parallel relationship withrespect to an axis extending in the direction of movement of the gradingmachine.

This application represents a continuation-in-part of my .co-pendingapplication Ser. No. 362,740, filed Apr. 27, 1964, now Patent No.3,303,589, and also certain improvements thereover.

This invention relates to controls for road graders and the like andmore particularly to a unique mounting for the circle frame on which theearth working blade of the road grader is attached in order to giveabsolute control and precision cutting when the automatic controls arebeing used.

Many automatic controls have been advanced for use with road graders,but these are usually very complex or are inaccurate. The problem arisesfrom the fact that the axis :of the circle frame, on which the earthworking blade is mounted, and consequently the vertical axis about whichthe earth working blade will rotate in order to change the anglethereof, is not perpendicular to the lane which is cut by the blade, orin other words, the cutting plane of the blade. The plane of themounting frame for the blade is not parallel to the plane cut by theblade. This is usually due to the fact that the circle frame is mountedthrough a drawbar that in turn is mounted with a ball joint adjacent thefront axle of the working blade, and the drawbar then slopes downwardlyto the circle frame causing the circle frame plane to be out of parallelwith the plane cut by the earth working blade.

When the plane of the circle frame is not parallel to the plane which iscut by the earth working blade, in a fore and aft direction, each timethe blade is rotated about its vertical axis to change the angle of theblade, the angle of the blade cutting plane in a transverse directionwill also change.

In order to overcome this problem, the device of the present inventiondiscloses a unique way of mounting the circle frame so that it can beadjusted to make the plane of the circle frame exactly parallel to theplane cut by the grader blade as the grader moves along over the earth.In doing so, the plane of the circle frame is held exactly parallel tothe cutting plane of the blade, in both fore and aft directions andtransverse direction. The linkage utilized comprises a four bar linkagewhich attaches between the controls for the raising and lowering of thecircle frame and the frame itself so that the position of the circleframe is controlled by the raising and lowering linkage. The transverseangle of the circle frame "ice and the blade can be changed, as can thedepth of cut, but the fore and aft angle does not change.

Also, as shown, a pendulum sensing unit is utilized for actuating thecontrols to maintain a desired transverse slope on the blade. Once theproper transverse slope of the cutting plane is reached, no matter wherethe blade is rotated about its vertical rotational axis, the sametransverse slope will be held, because the plane of the circle frame isparallel to the cutting plane that is desired, and rotation of the bladein this plane will mean that the blade will remain parallel to the planeregardless of its angular position.

The device is used primarily in finish work where very shallow cuts aremade. Thus the normal range of the blade in working position does notaffect the setting of the circle frame plane.

It is an object of the present invention to present a new control devicefor graders comprising a unique method of mounting the circle frame onwhich the blade is mounted, and automatic controls for use in connectiontherewith.

In the drawings,

FIG. 1 is a side elevational view of a road grader having a circle framemounted according to the teachings of the present invention installedthereon;

FIG. 2 is a fragmentary top plan view of the drawbar and front portionsof the circle frame made according to the present invention and taken ason line 2--2 of FIG. 1;

FIG. 3 is a fragmentary sectional view taken as on line 33 in FIG. 1;

FIG. 4 is a fragmentary sectional view and part hydraulic schematic viewtaken as on line 4-4 in FIG. 1;

FIG. 5 is a fragmentary top plan view of the circle frame portion of theroad grader of FIG. 1;

FIG. 6 is a sectional view of a pendulum sensing unit made according tothe present invention and taken as on line 6-6 in FIG. 5;

FIG. 7 is a fragmentary sectional view of the device of FIG. 6 as viewedfrom the rear thereof;

FIG. 8 is a schematic representation of an electrical circuit utilizedwith the sensing unit of the present invention; and

FIG. 9 is a fragmentary front view of the slope indicator used with thepresent invention.

Referring to the drawings and numerals of reference thereon, a roadgrader 15, which is conventionally made, as shown, the type made by theGalion Iron Works & Mfg. Co. of Galion, Ohio, is utilized. The graderhas an elongated frame 16 and is mounted on a plurality of wheels 17.The grader is powered from an engine 18 with suitable mechanism (notshown). A cab 19 is positioned on the main frame of the grader andhouses the grader operational controls illustrated generally at 20.

An earth working blade 21 is mounted through suitable brackets 22 to acircle frame 23.

The circle frame itself is rotatably mounted on and with respect to amounting frame assembly 24, which comprises, as shown, a front mountingmember 25 and a rear mounting member 26 which are joined togetherrigidly with a longitudinally extending member or frame 27. This canperhaps best be seen in FIG. 5. The circle frame itself is slidablymounted to the mounting frame 24 on slider brackets that are boltedthrough the rear member 26 with suitable bolts 31. The circle frame hasits inner peripheral edge notched to form teeth 32. The circle frame canbe rotated on the slider brackets about its upright axis through theuse, in this grader, of a hydraulic motor 33 that is controlled throughsuitable hydraulic controls, from the cab. The exact details of thesecontrols are not shown because this is conventionally 'done. Thehydraulic motor Bit-operates through a suitable gear reduction mechanismwhich engages the inner toothed edge of the circle frame to rotate theframe and attached blade.

The mounting assembly 24 is attached to the main frame of the graderthrougha drawbar linkage 34. The drawbar linkage 34 is attached to themounting frame 24 at the front cross member 25, through a pair of balljoint assemblies 35. The ball joint assemblies 35, as shown, have ballmembers 36, 36 fixedly attached to a bracket 37 in transversely spacedapart relationship, and the ball members 36 are mounted in housings 38which in turn are attached to the front cross member 25. As can be seen,the ball members are spaced quite widely apart and on opposite sides ofthe longitudinal axis of the drawbar linkage.

The ball joint assemblies 35 can be termed universal members and willpivot in all directions. As shown, however usage of the two ball jointassemblies will permit the mounting frame 24 and then thus the circleframe to pivot only about a transverse axis passing through the balljoint members. This axis is parallel to the plane of the circle frameand also perpendicular to the longitudinal axis of the drawbar.

The front end of the drawbar linkage 34 is mounted through a ball joint39 to the frame 16 of the grader at the front axle thereof. This can bemounted in the usual preferred manner which will permit the drawbarlinkage 34 to pivot from side to side, as well as up and down.

The height of the circle frame and mounting member 24 above the groundis controlled through the use of suitable linkage which is illustratedin FIG. 1, FIG. 3 and schematically in FIG. 4. As shown, a pair of rockshafts 41 and 42, respectively, are pivotally mounted on suitablebrackets 43 that in turn are mounted to the main frame 16 of the grader.The rock shafts 41 and 42 have separated control levers 44 and 45,respectively, fixedly attached thereto adjacent the rear portionsthereof. The control levers 44 and 45 are actuated through the use of apair of hydraulic cylinders 46 and 47, respectively, which are attachedto a frame member 48 of the grader and they have extendable cylinderrods 49 which in turn are pivotally attached to the control levers 44and 45. As the cylinders 46 and 47 are extended or retracted, thecontrol levers 44 and 45 will move, causing the rock shafts 41 and 42 topivot as desired under their control. The hydraulic cylinders 46 and 47are controlled through hydraulic control valves 52 and 53, respectivelywhich have control handles 54 and 55. The hydraulic pump illustratedschematically at 56 is connected through suitable pressure lines 57 tothe control valves 52 and 53. Return lines 58 are connected to areservoir 59 to complete the hydraulic circuit to the valves. When thevalve handles are operated, they will move a spool valve inside therespective valve assembly 52 and 53 to direct pressure either throughthe pressure line 60 or 61 which would cause the rods 49 and 50 toextend or through pressure line 62 or 63, respectively, which wouldcause the rod 49 or 50 to retract.

Each of the rock shafts 41 and 42 have two lift arms 64 and 65respectively, attached at their forward ends thereof. As shown, the arm64 is attached near the intermediate portion of the rock shaft and thearm 65 is attached at the forward end of the rock shaft. Thus, when therock shafts rotate, the arms 64 and 65 will also rotate. It should benoted that the arms 64 and 65 extend outwardly from the rock shaft whilethe levers 44 and 45 extend inwardly. In the conventional situation therock shafts have only one arm each, which corresponds to theintermediate arms shown. To convert standard units to devices of thepresent invention, the conventional rock shafts can be extended and thefront lift arms 65 added.

The arms 64, which are attached to the rock shaft 41 and 42, areconnected to the circle frame through adjustable lift links 66. Thelinks 66 are connected to the arms 64 through ball or swivel j i orother suitable connections illustrated at 67 and are also connected tothe outer ends rear cross frame member 26 through similar ball joints 68or other connections. The links 66 are, as shown, adjustable inlongitudinal length. They comprise an outer section and a telescopinginner section which can be pinned through suitable pins to the outersection. Thus the length of the links 66 can be adjusted.

The arms 65 have forward lift links 71 attached thereto with ball joints72, and the lower link ends of the links 71 are attached to the outerends of the front cross member 25 of the mounting frame 24 of the circleframe with suitable ball joints or connections 73.

The front links 71 are also longitudinally adjustable, comprising anouter member and a telescoping inner member at the lower end thereof.However, instead of merely pinning the inner and outer members of eachlink together, the lower member of each link 71 has suitable bolts 74attached thereto at the ball joints 73 and which extend up throughopenings in ears 75 which in turn are welded to the outside of the outermember of the link. The bolts pass through provided openings in the cars75 and suitable nuts 76 are threaded on opposite sides of the cars sothat the nuts can be threaded to obtain a very precise adjustment inlength of each of the links 71. The reason for making the preciseadjustment of the forward links 71 will be apparent as the descriptionproceeds. The links are adjusted to position wherein the plane of thecircle frame is parallel to the cutting plane of the earth workingblade, when the blade is at Working depth. The depth of the blade andalso its transverse angle can be set manually be operating the valves 52and 53. Normally, the cut is very shallow and is not adjusted very muchwhen working.

The control valves 52 and 53, besides being manually operative, are alsooperated by solenoids, if desired. The solenoids are used when automaticleveling of the unit is to be changed. The controls for the solenoidwill be subsequently explained, but it can be seen that the handle 54has an actuating link which extends to engage the spool of the valve 52and this actuating link in turn is connected as at 111 to a solenoidoperated arm 112 that is actuated from a solenoid 113 which in turn ismounted to the base of the grader. The solenoid 113 is actually twosolenoids in one, and will operate the arm 112 in either direction ofmovement along its longitudinal axis.

The lever or control handle 55 has an actuating link 115 attachedthereto and the actuating link is connected as at 116 to a secondsolenoid arm 117 that is controlled by a second solenoid 118. The secondsolenoid 118 is also connected to the frame of the grader, and, as willbe apparent as the description proceeds, actually contains twosol'e'noid coils so that the arm 117 can be actuated in either directionalong its longitudinal axis. Each of the solenoids 113 and 118 areidentical in construction, except that they are connected to controldifferent valves.

The transverse angle of the circle frame and earth working blade, whichis attached to the frame, also can be automatically controlled throughthe use of a horizon sensing case 80, which is mounted onto the mountingmember 24 for the circle frame. A pendulum sensing unit is utilized, andwhen the circle frame tilts away from the normal operating position, thependulum is used to actuate suitable controls (valve 52 or 53) to bringthe circle frame back to its predetermined original position. The case80 is pivotally mounted to a mounting bracket 81 through the use of apin 82. The pin 82 is fixed to the case front wall and passes through anupright plate 86 of the bracket 81. The bracket 81, in turn, has a bracemember 83 that is attached to the longitudinally extending member 27 ofthe mounting frame 24 for the circle frame.

The mounting bracket 81 is attached so that the axis of the pin 82 isparallel to the longitudinal axis of the grader, with the circle framecentered under the grader frame. The pivoting of the case 80 about itspivot 82 will permit an artificial plane to be established at which thecircle frame will remain under control of the horizon sensing case 80.

In order to control the pivoting of the case 80 about its pin 82, alinkage 84 which is pivoted to the case at 85 is utilized. The operationof this linkage and the manner in which it fixes the angularrelationship of the horizon sensing pendulum case 80 with respect to thesupport mounting plate 81 will be more fully explained later.

As perhaps best seen in FIGS. 6 and 7, inside the pendulum case orhorizon sensing case 80 a pendulum 90 is mounted on a pendulum shaft 91which in turn is rotatably mounted on suitable bearings 92, 92 in thecase 80. The bearings 92, 92 are antifriction bearings and permit theshaft 91 to rotate very easily. The pendulum 90 is mountted for movementabout the longitudinal axis of the shaft 91 (which is parallel to theaxis of pin 82) but is restrained from movement longitudinally along theshaft. The pendulum has a pair of integral vanes 93, 93 positioned onthe opposite side thereof. These vanes are spaced very slightly inwardlyfrom the corresponding edges of the case 80. Two other side surfaces 94,94 of the pendulum are spaced inwardly a relatively greater distancefrom the corresponding side edges of the case 80. This is to allow thependulum to move from side to side within the pendulum case as it pivotsabout the axis of the shaft 91. A pair of stop bolts 95, 95 arethreadably mounted as at 96 with respect to the side edges of thependulum case 43. The bolts are aligned with side surfaces 94, 94 of thependulum, and are adapted to engage these side surfaces to prevent thependulum from swinging farther than necessary to operate the controlsystem. The pendulum case 80 is filled with a highly refined oilindicated at 97 which dampens the movement of the pendulum as it swingsabout the axis of shaft 91. A small clearance between vanes 93 in thecorresponding sides of the pendulum case constricts the flow of oil asthe pendulum swings.

Pendulum shaft 91 has an end portion 101 which extends outwardly fromthe case 80 into a housing 99 which is fixed to the case. An actuatinglug or ear 102 is fixedly attached to the shaft end portion 101. As bestseen in FIG. 7, a first switch 103 is mounted on the housing 99 on oneside of the lug 102 and a second switch 104 is mounted on the housing inthe opposite side of the lug 102. Actuating buttons 108, 108 for theseswitches are positioned adjacent the lug.

As can be seen in FIG. 8, which is the electrical circuit diagram forthe unit, a motor 105 is connected through a source of electromotiveforce 106 through a main power on-oif switch 107.

The motor 105, when the main switch 107 is closed, is energized and thisin turn drives a cam member 121 which actuates a micro-switch 122, byopening and closing it intermittently. The micro-switch 122, when it isclosed, connects the source of electromotive force 106 through each ofthe switches 103 and 104 to a reversing switch 123. This reversingswitch can be a three position switch in which the center of disconnectposition can serve as the off switch for the control apparatus. Aseparate power onotf switch 107 is also utilized if desired. Thereversing switch, in turn, is connected to a double pole double throwswitch 124, which will connect the switches 103 and 104 to solenoid 113or to solenoid 118, whichever is to be used in operation of the unit. Itshould be explained that during the automatic operation of the unit,only one of the hydraulic control valves is automatically controlled.Thus, only one of the solenoids needs to be operated. The otherhydraulic control valve can be manually actuated to set the depth of theblade and the automatic control will actuate the other valve to causethe blade to assume its predetermined slope or position at the newdepth.

If the angle of the blade is reversed (as shown the left end of theblade is leading, if reversed the right end of the blade would lead),then the other solenoid will be used for operation. As shown, thesolenoid 113 is connected for operation. It should be understood, again,that the solenoid 118 can also be connected, and will operate in thesame manner as the solenoid 113, merely by throwing the double poledouble throw switch 124 to its opposite position.

Assuming that the switch 124 is positioned as shown, connecting thesolenoid 113 into the circuit, when the reversing switch 123 is thrownto the upward position as shown in FIG. 8, the power will flow from themicro switch 122 (intermittently) and switch 103 (when closed) to arelay 125 which will cause a first solenoid coil 126 to be energized.:Power will flow through the micro-switch 122 and the switch 104 (whenclosed) to a relay 127 which will power a second solenoid coil 128. Withthe reversing switch in this upward position, tilting of the pendulumcase to cause the lug 102 to close switch 104 will cause the secondsolenoid coil 108 to be energized intermittently every time themicro-switch 122 closes to permit power to flow therethrough and thesolenoid armature 129 will be moved to the left as seen in FIG. 8.Solenoid operating arm 117 is integral with the armature 129 and willalso move to the left. When the micro-switch 122 is not passing thecurrent, (the cam 121 permits the micro-switch to open) the springs 131and 132 will center the armature 129 to the position as seen in FIG. 8.

Movement of the armature will actuate the handle of valve 52 indirection to cause the cylinder 46 to rotate rock shaft 41 and changethe position of the circle frame in a manner to cause the lug 102 tomave away from switch 104.

When the sensing case moves so that the lug 102 under the urging of thependulum 100 closes switch 103, current through the micro-switch 122will cause current to flow through the first solenoid coil 126 and thesolenoid arm 117 and armature 129 will move to the right as seen in FIG.8. When the current stops flowing through the switch 122, because of theswitch opening, the springs 131 and 132 will again center the armature.

The action described above results in a series of intermittentincremental movement on the arm 117 in direction determined bypositioning of the reversing switch 123 and by the relationship of thependulum 100 and the lug 102 with respect to the horizon sensing case 80and the switches mounted with respect thereto. The controls are set sothat the left links will be moved to set the transverse slope of thecircle frame in a position wherein the pendulum will no longer actuatethe switches 103 or 104.

The action will be exactly the same for the solenoid 118 (the internalconstruction is the same as the solenoid 113) when the double poledouble throw switch 124 is reversed in position. In that case, thecurrent will flow either to a relay 133 or to a relay 134, dependingupon whether the switch 103 or 104 is closed. The relays in turn willcontrol suitable solenoid coils inside the solenoid assembly 118 to movethat solenoid arm 112 in the required position to obtain the propermovement of the cylinders, and their corresponding rock shafts to inturn adjust the circle frame and blade properly to center the pendulum.

With the parts in electrical circuitry positioned as shown in FIG. 8, sothat the solenoid 113 is operated, movement of the solenoid operatingarm 117 away from the main solenoid 118 will cause the lever 55 to bepivoted, actuating the valve 53 in the first direction, compressing thecylinder 50 which in turn will rotate lever 45 and rock shaft 42. Thismeans that the arms 64 and 65 attached to rock shaft 42 will be raisedthereby lifting the links 66 and 71 and raising that side of the circleframe assembly. This will change the angular relationship of the circleplane and consequently the work plane determined by the loci of movementof the lower working edge 135 of the grader blade 21. The solenoidoperating arm is only in the activated position momentarily while themicro-switch 122 is passing current, the increment of angulardisplacement of the operating plane of the grader blade will be slight.If the incremental movement is not sufficient to cause the lug 62 tomove into clearing relationship with respect to the go switch whichoriginally chartered the movement (103 or 104) then when themicro-switch 122 next closes, a further incremental movement in the samedirection will take place. As soon as this small movement is sufficientto cause the switch 103 or 104 moved to the open condition, no suchfurther movement of the controls will be forthcoming. The pendulumcontrols the lug, and the pendulum always seeks a vertical position.

Should the grader operator want the earth working grader blade 21 tomake a deeper or shallower cut while the solenoid 113 is in theoperating position, he merely has to operate the second control handle54 for the valve 52 to cause the opposite side of the circle framemounting member 24 and consequently the circle frame itself to be raisedor lowered as desired. As the pendulum in the case, which is mounted onthe circle frame member, attempts to maintain its vertical relationship,it will then be tilted and will activate one of the switches 103 or 194-and the automatic control mechanism just described will operate to raiseor lower the opposite side of the circle frame to maintain orre-establish the desired working plane.

The angle of the plane passing through the axis of the shaft 91supporting the pendulum and the pin 82, will always seek tobe-perpendicular to the horizontal when the actuating mechanism is inoperation, because the pendulum will seek the vertical direction due togravity and will actuate the switches 103 or 104 until it is at thevertical position and the lug 102 no longer contacts either of theseswitches. The angle of plane with respect to the plane of the circleframe can be mechanically changed through the linkage 84 in order toestablish an angular relationship between the plane of the circle frameand the horizontal in a transverse direction. This is done by utilizingthe connection 135 between the linkage 84 and the top portion of thecase 80. A reversible motor 141 is mounted with respect to the mountingmember 83 and operating through a gear box 142 can be made to extend orshorten the link 84 longitudinally in its own axis, thereby rotating thecase 30 about the pivot pin 82. The reversible motor 141 can be of anysuitable type which will drive suitable gearing that will extend orshorten the link 84. Usually the internal member of the link 84 will betubular and have an internal nut that is threaded over a shaft which inturn is rotationally driven through the Worm gearing 142 by the motor141. As the shaft rotates it will cause the nut and the inner portion ofthe link 84 to shorten or lengthen with respect to the outer portion ofthis link. The motor 141 itself is mounted on an arm 143 that isattached to the frame mounting member 83.

In order to indicate the extent of the rotation on the case 80 withrespect to the frame plate 81, a link 144 can be attached to the case inany suitable manner and in turn can control (through a pivotingconnection) an indicator rod 145 which is pivotally mounted as at 148(see FIG. 9) to an upright bracket 146 that in turn is attached to anextension of arm 143 and operates in conjunction with an indicator plate147, which will have suitable indicia thereon. When the case 86 istilted, thereby establishing an inclined cutting plane for the blade, itwill cause the link 144 to move, pivoting the indicator arm 145 withrespect to the plate to show the angle of the case, and thus slope ofthe plane of the circle frame when the automatic control has made thenecessary adjustments. Any suitable indicating mechanism can be used,but as shown, the plate 147 can be read from the cab of the grader toeasily show what slope is being cut by the lower cutting edge 135 of theblade 21.

The circuit for operating the reversible motor 141 is, as seen in FIG.8, wherein a reversible switch 150 will be normally positioned in theneutral or off condition (it is shown on) and can be manuallymanipulated to cause the motor to run frontward or backward thus toadjust the angular relationship of the case to the desired work plane ineither direction of slope, by lengthening or shortening the link 84. Theangular relationship of the case 80 to the circle frame plane will beindicated by the mechanism 145-147 which the operator will watch as heoperates the motor 121. As soon as the automatic controls are activatedthe device of the invention will conform the Work plane of the graderblade to that indicated on the indicia plate by the indicator needle.

When the device is to be used, the lift links 66 and 71 are adjusted inlength so that the plane of the circle frame is exactly parallel to thecutting plane. The adjustment is made when the blade is at its normalcutting depth. Because the circle frame is held at four points and islifted at two spaced points on each side whenever a rock shaft isactuated the angular position of the circle frame in fore and aftdirection does not change at all. While the transverse slope of theplane of the circle frame can be changed, the fore and aft slope cannotbe changed. As the circle frame is raised or lowered, the ball joints 35permit the circle frame to move up and down without changing the angleof its plane in fore and aft direction. The angle of the drawbar changesbut the circle frame does not. The great advantage from operating thecircle frame in this manner is that when the blade 21 is rotated (thecircle frame and blade are rotated together through the gear case 30)the transverse angle of the plane cut by the cutting edge as the gradermoves along the ground will not change no matter what the angularposition of the grader blade about its upright axis is. Previous deviceswhere the circle frame plane inclined in the fore and aft directionchanging the angle of the grader blade about its upright axis ofrotation would change the trans verse slope of the cutting plane of theblade as well.

Previously, attempts were made to compensate for this inclination of thecircle frame in fore and aft direction, but it has now been found thatby mounting the circle frame so that it is held parallel to the cuttingplane the problems are eliminated. Once the desired slope has been setin transverse direction, rotation of the circle frame and the graderblade attached thereto will not change this transverse angle. The use oftwo lift links on each side of the circle frame which are on a commoncontrol means that the lifting of one side or the other does not changethe fore and aft angle.

Further, the usual operation of the device will leave the circle framecentered underneath the grader frame so that the axis of shaft 92 willbe parallel to the longitudinal axis of movement of the grader blade.The road graders presently being used have provisions thereon forshifting the blade from one side to the other with respect to itssupport members 22 so that the circle frame does not have to be shiftedfrom side to side. This means that it is not necessary to compensate forchanges in angle of the pivotal axis of the pendulum, because thispivotal axis will usually remain parallel to the direction of movement.

What is claimed is:

1. In a grading machine, the combination of a machine frame movable overthe ground in a normal direction of travel, a mounting frame, a circleframe mounted on the mounting frame and rotatable with respect theretoabout a substantially upright circle frame axis, a blade mounted on andcarried by the circle frame with its working edge in a planeperpendicular to the circle frame axis and parallel to the plane ofmovement of the circle frame, means to support said mounting frame onsaid machine frame including linkage means for raising and lowering saidmounting frame, said linkage means being positioned on opposite sides ofthe mounting frame to permit selectively lifting of one side or theother of said mounting frame, and including means to stabilize themounting frame in fore and aft direction so that as the mounting frameis raised or lowered the plane of the circle frame does not change inangle with repsect to the cutting plane of the blade as the respectivelinkage means are moved up and down, said linkage means constituting thesole means to stabilize the mounting frame, and drawbar means pivotallyattached to the forward portions of said machine frame and pivotallyattached to the mounting frame about a pivot axis transverse to themachine frame and parallel to the plane of the circle frame to permitmovement of the mounting frame without changing the angle of the circleframe in fore and aft direction.

2. The combination as specified in claim 1 wherein the linkage meansbetween said machine frame and said mounting frame includes four uprightlinks, two of said links being positioned adjacent each of the oppositesides of the mounting frame, and said two links on each side beingspaced apart in fore and aft direction.

3. The combination as specified in claim 2 wherein said two links oneach side of the machine are controlled by a separate common controlshaft on each side of the machine frame, means to pivotally mount saidcontrol shafts on said machine frame above the mounting frame and powermeans to separately control movement of said shafts.

4. The combination as specified in claim 3 wherein at least one link oneach side of the machine has means thereon for adjusting the lengththereof to level the mounting frame.

5. The combination as specified in claim 1 and a pendulum mounted onsaid mounting frame and having a normal position and control means torestore said mounting frame to a predetermined position when saidpendulum is moved from its normal position.

6. The combination as specified in claim 5 wherein said control meansincludes an interrupter means to pulsate the movement of said mountingframe to its predetermined position in incremental steps, saidinterrupter means comprising a mechanical cam operating tointermittently disable said control means.

7. In a grading machine, the combination of a machine frame movable overthe ground in normal direction of travel, a mounting frame, a circleframe mounted to this mounting frame and rotatable with respect theretoabout a circle axis, a blade mounted on the circle frame with itsworking edge in a plane substantially parallel to the plane of rotationof the circle axis, a drawbar member mounted to forward portions of saidmachine frame for pivotal movement and to the mounting frame so as to bepivotally movable about an axis parallel to the plane of the circleframe and perpendicular to the longitudinal axis of said drawbar member,selectively actuable lift link means mounted to said mounting member onopposite sides of said mounting frame, said lift link meansindependently supporting said mounting frame for up and down movement,and preventing said mounting frame from tilting about a transverse axisso that said mounting frame will be raised up and down 'without changingthe angle of the plane of the circle frame in fore and aft directions,said lift link means constituting the sole means for preventing themounting frame from tilting about a transverse axis, a pendulum controlmember, means to pivotally mount said pendulum on said mounting frame,and control means actuated by said pendulum for restoring the transverseangle of the plane of the circle frame whenever said pendulum is movedfrom a predetermined position.

8. The combination as specified in claim 7 'wherein said pendulum ismounted in a case and the case is pivotally mounted to the mountingframe, and means to tilt said pendulum case to cause said pendulum toope-rate said control means to establish a predetermined slope intransverse direction of said circle frame.

9. The combination as specified in claim '8 wherein said lift link meansare comprised as four separate links, two of said links being mountedadjacent each side of said mounting frame, each pair of links on eachside of said mounting frame being raised by a common control member.

10. The combination as specified in claim 9 wherein said drawbar isattached to said mounting frame with two ball joint members which aretransversely spaced apart an equal distance on opposite sides of theaxis of pull of said drawbar, and are spaced a substantial distanceapart to give stability to the mounting member.

11. The combination as specified in claim 7 wherein said control meansincludes power actuated lift mechanism and an electrical circuitcontrolling operation of said power actuated lift mechanism, saidcontrol means further including a cam member, means to rotate said cammember, a switch in said electrical circuit, and said cam member beingoperative to intermittently open and close said switch as it rotates.

References Cited UNITED STATES PATENTS 1,720,189 7/1929 Jackson 335-73 X1,732,892 10/1929 Hinds 37-156 2,074,081 3/1937 Burns 37-1'57 2,497,7782/ 1950 Lado 37-156 2,904,911 9/1959 Colee.

2,941,319 6/1960 Beemer et al 37-156 3,094,796 6/1963 Atchley 37-156ABRAHAM G. STONE, Primary Examiner.

ALAN KOP'ECKI, Assistant Examiner.

US. Cl. X.R.

